Tool Time: Test Connectivity to Remote Email Servers with TestMX

It’s probably happened to you at some
point: Users are unable to email people
at a specific domain. As the administrator,
it’s your job to find and solve the
problem.

As you divide and conquer your
way to a solution, you’ll no doubt
want to try to “manually” connect to
the destination email server. You can
accomplish this by using Telnet to
connect to port 25 of the destination
server. To find that server’s host name,
you can use a command-line utility
such as Nslookup or a web-based DNS
tool such as the one at www.iptools.com. However, there’s an easier
way to quickly determine whether
your email server can connect to the
destination server: Use TestMX.

You can download TestMX from
www.dataenter.co.at/download.htm.
After doing so, copy testmx.exe to the
root of the C drive on your email server.
Installing it on an email server rather
than a PC prevents problems with firewalls
and reverse lookups and ensures
that you’re comparing apples to apples.

To use TestMX, open up a command
prompt and type:

testmx –dDomain

where Domain is the name of the
domain that you want to test. Note that
there should be no space between the
–d and the domain name. TestMX then
takes care of finding and connecting to
the email servers in that domain.

That’s it! In just a few short seconds,
you can use TestMX to confirm connectivity
to the remote email server. With
this information, you can then move to
the next step in your troubleshooting
process.